Cleanup: Clean previous commit.

Dislike the idea of passing a string into build_cli. By removing
a call to default_value we can side-step the problem.

Downside is we lose the error log if a user provides a bad depth

build.rs

@@ -6,8 +6,7 @@ include!("src/cli.rs");
 fn main() -> Result<(), Error> {
     let outdir = "completions";
     let app_name = "dust";
-    let max_depth = usize::MAX.to_string();
-    let mut cmd = build_cli(&max_depth);
+    let mut cmd = build_cli();
 
     generate_to(Bash, &mut cmd, app_name, outdir)?;
     generate_to(Zsh, &mut cmd, app_name, outdir)?;